In case of a vehicle which equips with an internal combustion engine, the fuel injection time and ignition time are adjusted based on a drive condition, etc. of the vehicle. In case of the multiple-cylinder engine, it needs to accurately synchronize the fuel injection time and ignition time of each cylinder in order to inhibit an engine power degradation and any harmful gas emission which may occur due to an incomplete combustion.
In order to carry out the synchronization of such an engine, it needs to accurately detect the rotation positions of a crank shaft of each cylinder. In a related art, a conventional technology to accurately detect the rotation positions of the crank shaft. According to the conventional technology, a crank shaft position sensor and a cam sensor are employed so as to accurately detect the rotation positions of the crank shaft.
The crank shaft position sensor is configured to detect an angle of rotation and revolution of the crank shaft by detecting the protrusion-shaped teeth formed on a synchronization revolving body of the crank shaft and output them in a pulse type crank signal. The cam sensor is configured to detect the position of a camshaft by recognizing an angle identification protrusion formed at the synchronization revolving body of the camshaft for intake and exhaust, detect a falling edge time and a rising edge time, and output them as pulse type cam signals. The electronic control unit (ECU) is able to recognize the position of the piston of each cylinder with the aid of the crank signal and recognize where the piston of each cylinder is currently positioning, by using the cam signal. The ECU therefore will adjust the injection time and the ignition time of the fuel of each cylinder by using them.